Systems and methods for carrier aggregation

ABSTRACT

A User Equipment (UE) for performing carrier aggregation is described. The UE includes a processor and instructions stored in memory that is in electronic communication with the processor. The UE determines an uplink control information (UCI) transmission cell in a wireless communication network with at least one frequency-division duplexing (FDD) cell and at least one time-division duplexing (TDD) cell. The UE also selects a first cell for FDD and TDD carrier aggregation. The UE further determines a set of downlink subframe associations for the first cell that indicate at least one UCI transmission uplink subframe of the UCI transmission cell. The UE additionally sends Physical Downlink Shared Channel (PDSCH) Hybrid Automatic Repeat Request Acknowledgement/Negative Acknowledgement (HARQ-ACK) information in the UCI transmission uplink subframe of the UCI transmission cell.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/807,592 entitled “SYSTEMS AND METHODS FOR CARRIER AGGREGATION,” filedJul. 23, 2015, which is a continuation of U.S. patent application Ser.No. 14/444,645 entitled “SYSTEMS AND METHODS FOR CARRIER AGGREGATION,”filed Jul. 28, 2014 and now issued as U.S. Pat. No. 9,124,401, which isa continuation of U.S. patent application Ser. No. 13/665,558 entitled“SYSTEMS AND METHODS FOR CARRIER AGGREGATION,” filed Oct. 31, 2012 andnow issued as U.S. Pat. No. 8,811,332, which are all hereby incorporatedby reference in their entirety.

TECHNICAL FIELD

The present disclosure relates generally to communication systems. Morespecifically, the present disclosure relates to systems and methods forcarrier aggregation.

BACKGROUND

Wireless communication devices have become smaller and more powerful inorder to meet consumer needs and to improve portability and convenience.Consumers have become dependent upon wireless communication devices andhave come to expect reliable service, expanded areas of coverage andincreased functionality. A wireless communication system may providecommunication for a number of wireless communication devices, each ofwhich may be serviced by a base station. A base station may be a devicethat communicates with wireless communication devices.

As wireless communication devices have advanced, improvements incommunication capacity, speed, flexibility and/or efficiency have beensought. However, improving communication capacity, speed, flexibilityand/or efficiency may present certain problems.

For example, wireless communication devices may communicate with one ormore devices using a communication structure. However, the communicationstructure used may only offer limited flexibility and/or efficiency. Asillustrated by this discussion, systems and methods that improvecommunication flexibility and/or efficiency may be beneficial.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating one configuration of one or moreevolved Node Bs (eNBs) and one or more User Equipments (UEs) in whichsystems and methods for carrier aggregation may be implemented;

FIG. 2 is a flow diagram illustrating one implementation of a method forperforming carrier aggregation by a UE;

FIG. 3 is a flow diagram illustrating one implementation of a method forperforming carrier aggregation by an eNB;

FIG. 4 is a diagram illustrating one example of a radio frame that maybe used in accordance with the systems and methods disclosed herein;

FIG. 5 is a diagram illustrating some Time-Division Duplexing (TDD)uplink-downlink (UL-DL) configurations in accordance with the systemsand methods described herein;

FIG. 6 illustrates a specific implementation of association timings of aTDD cell with UL-DL configuration one;

FIG. 7 illustrates the association timings of a Frequency DivisionDuplexing (FDD) cell;

FIG. 8 is a flow diagram illustrating a more specific implementation ofa method for performing carrier aggregation by a UE;

FIG. 9 is a flow diagram illustrating a more specific implementation ofa method for performing carrier aggregation by an eNB;

FIG. 10 illustrates various components that may be utilized in a UE; and

FIG. 11 illustrates various components that may be utilized in an eNB;

FIG. 12 is a block diagram illustrating one configuration of a UE inwhich systems and methods for performing carrier aggregation may beimplemented; and

FIG. 13 is a block diagram illustrating one configuration of an eNB inwhich systems and methods for performing carrier aggregation may beimplemented.

DETAILED DESCRIPTION

A UE for performing carrier aggregation is disclosed. The UE includes aprocessor and memory that is in electronic communication with theprocessor. Executable instructions are stored in the memory. The UEdetermines an uplink control information (UCI) transmission cell in awireless communication network with at least one FDD cell and at leastone TDD cell. The UE also selects a first cell for FDD and TDD carrieraggregation. The UE further determines a set of downlink subframeassociations for the first cell that indicate at least one UCItransmission uplink subframe of the UCI transmission cell. The UEadditionally sends Physical Downlink Shared Channel (PDSCH) HybridAutomatic Repeat Request Acknowledgement/Negative Acknowledgement(HARQ-ACK) information in the UCI transmission uplink subframe of theUCI transmission cell.

The UE may also determine a PDSCH scheduling for the first cell. ThePDSCH scheduling may include cross-carrier scheduling. The scheduling ofthe first cell may be based on a scheduling cell timing. The PDSCHscheduling for the first cell may occur in a downlink allocationsubframe of the scheduling cell. The scheduling cell may be a TDD cell.The UE may also determine a Physical Uplink Shared Channel (PUSCH)scheduling and PUSCH HARQ-ACK associations for the first cell.

The set of downlink subframe associations for the first cell may includea PDSCH association timing of the UCI transmission cell. The UCItransmission cell may be a FDD cell and the first cell may be a TDDcell.

Determining the set of downlink subframe associations for the first cellmay include maintaining a PDSCH association timing of the first cell.The UCI transmission cell may be a FDD cell and the first cell may be aTDD cell.

The UE may additionally determine a primary cell (PCell). The PCell maybe a TDD cell and the UCI transmission cell may be a reference cell. Thereference cell may be a FDD cell.

The UE may also determine a second UCI transmission cell for UCItransmission. The UCI transmission cell and second UCI transmission cellmay utilize different duplexing. The UE may additionally send PDSCHHARQ-ACK information in the UCI transmission uplink subframe of the UCItransmission cell. The PDSCH HARQ-ACK information for the FDD cell maybe sent by the UCI transmission cell and the PDSCH HARQ-ACK informationfor the TDD cell may be sent by the second UCI transmission cell. ThePDSCH HARQ-ACK information may be sent on one of a Physical UplinkControl Channel (PUCCH) or a PUSCH.

An eNB for performing carrier aggregation is also described. The eNBincludes a processor and memory that is in electronic communication withthe processor. Executable instructions are stored in the memory. The eNBdetermines an UCI transmission cell in a wireless communication networkwith at least one FDD cell and at least one TDD cell. The eNB alsoselects a first cell for FDD and TDD carrier aggregation. The eNBfurther determines a set of downlink subframe associations for the firstcell that indicate at least one UCI transmission uplink subframe of theUCI transmission cell. The eNB additionally receives PDSCH HARQ-ACKinformation in the UCI transmission uplink subframe of the UCItransmission cell.

A method for performing carrier aggregation by a UE is also described.The method includes determining an UCI transmission cell in a wirelesscommunication network with at least one FDD cell and at least one TDDcell. The method also includes selecting a first cell for FDD and TDDcarrier aggregation. The method further includes determining a set ofdownlink subframe associations for the first cell that indicate at leastone UCI transmission uplink subframe of the UCI transmission cell. Themethod additionally includes sending PDSCH HARQ-ACK information in theUCI transmission uplink subframe of the UCI transmission cell.

A method for performing carrier aggregation by an eNB is also described.The method includes determining an UCI transmission cell in a wirelesscommunication network with at least one FDD cell and at least one TDDcell. The method also includes selecting a first cell for FDD and TDDcarrier aggregation. The method further includes determining a set ofdownlink subframe associations for the first cell that indicate at leastone UCI transmission uplink subframe of the UCI transmission cell. Themethod additionally includes receiving PDSCH HARQ-ACK information in theUCI transmission uplink subframe of the UCI transmission cell.

The 3rd Generation Partnership Project, also referred to as “3GPP,” is acollaboration agreement that aims to define globally applicabletechnical specifications and technical reports for third and fourthgeneration wireless communication systems. The 3GPP may definespecifications for next generation mobile networks, systems, anddevices.

3GPP Long Term Evolution (LTE) is the name given to a project to improvethe Universal Mobile Telecommunications System (UMTS) mobile phone ordevice standard to cope with future requirements. In one aspect, UMTShas been modified to provide support and specification for the EvolvedUniversal Terrestrial Radio Access (E-UTRA) and Evolved UniversalTerrestrial Radio Access Network (E-UTRAN).

At least some aspects of the systems and methods disclosed herein may bedescribed in relation to the 3GPP LTE, LTE-Advanced (LTE-A) and otherstandards (e.g., 3GPP Releases 8, 9, 10 and/or 11). However, the scopeof the present disclosure should not be limited in this regard. At leastsome aspects of the systems and methods disclosed herein may be utilizedin other types of wireless communication systems.

A wireless communication device may be an electronic device used tocommunicate voice and/or data to a base station, which in turn maycommunicate with a network of devices (e.g., public switched telephonenetwork (PSTN), the Internet, etc.). In describing systems and methodsherein, a wireless communication device may alternatively be referred toas a mobile station, a UE, an access terminal, a subscriber station, amobile terminal, a remote station, a user terminal, a terminal, asubscriber unit, a mobile device, etc. Examples of wirelesscommunication devices include cellular phones, smart phones, personaldigital assistants (PDAs), laptop computers, netbooks, e-readers,wireless modems, etc. In 3GPP specifications, a wireless communicationdevice is typically referred to as a UE. However, as the scope of thepresent disclosure should not be limited to the 3GPP standards, theterms “UE” and “wireless communication device” may be usedinterchangeably herein to mean the more general term “wirelesscommunication device.”

In 3GPP specifications, a base station is typically referred to as aNode B, an eNB, a home enhanced or evolved Node B (HeNB) or some othersimilar terminology. As the scope of the disclosure should not belimited to 3GPP standards, the terms “base station,” “Node B,” “eNB,”and “HeNB” may be used interchangeably herein to mean the more generalterm “base station.” Furthermore, the term “base station” may be used todenote an access point. An access point may be an electronic device thatprovides access to a network (e.g., Local Area Network (LAN), theInternet, etc.) for wireless communication devices. The term“communication device” may be used to denote both a wirelesscommunication device and/or a base station.

It should be noted that as used herein, a “cell” may refer to any set ofcommunication channels over which the protocols for communicationbetween a UE and eNB that may be specified by standardization orgoverned by regulatory bodies to be used for International MobileTelecommunications-Advanced (IMT-Advanced) or its extensions and all ofit or a subset of it may be adopted by 3GPP as licensed bands (e.g.,frequency bands) to be used for communication between an eNB and a UE.“Configured cells” are those cells of which the UE is aware and isallowed by an eNB to transmit or receive information. “Configuredcell(s)” may be serving cell(s). The UE may receive system informationand perform the required measurements on all configured cells.“Activated cells” are those configured cells on which the UE istransmitting and receiving. That is, activated cells are those cells forwhich the UE monitors the physical downlink control channel (PDCCH) andin the case of a downlink transmission, those cells for which the UEdecodes a PDSCH. “Deactivated cells” are those configured cells that theUE is not monitoring the transmission PDCCH. It should be noted that a“cell” may be described in terms of differing dimensions. For example, a“cell” may have temporal, spatial (e.g., geographical) and frequencycharacteristics.

The systems and methods disclosed herein describe carrier aggregation.In some configurations, the systems and methods disclosed hereindescribe LTE enhanced carrier aggregation (eCA) with hybrid duplexing.For example, association timings are described for a case when a PCellis configured with frequency division duplexing (FDD) and a secondarycell (SCell) is configured with time division duplexing (TDD).Additionally, association timings for a case when a PCell is configuredwith TDD and a SCell is configured with FDD are also described.

Currently, there are two LTE duplex systems, FDD and TDD. However, undercurrent approaches, FDD and TDD systems cannot work together for CA. Forexample, under known approaches (e.g., LTE Rel-10 (hereafter “Rel-10”))and proposed approaches (e.g., LTE Rel-11 (hereafter “Rel-11”)), carrieraggregation (CA) is allowed for either multiple FDD cells, or multipleTDD cells, but not a hybrid of both types of cells.

Carrier aggregation refers to the concurrent utilization of more thanone carrier. In carrier aggregation, more than one cell may beaggregated to a UE. In one example, carrier aggregation may be used toincrease the effective bandwidth available to a UE. The same TDDuplink-downlink (UL-DL) configuration has to be used for TDD CA inRel-10, and for intra-band CA in Rel-11. In Rel-11, inter-band TDD CAwith different TDD UL-DL configurations is supported. The inter-band TDDCA with different TDD UL-DL configurations may provide the flexibilityof a TDD network in CA deployment. Furthermore, enhanced interferencemanagement with traffic adaptation (eIMTA) may allow flexible TDD UL-DLreconfiguration based on the network traffic load. However, CA in ahybrid duplexing network (e.g., a network with both FDD and TDD cells)is not supported in any current approach. It should be noted that theterm “concurrent” and variations thereof as used herein may denote thattwo or more events may overlap each other in time and/or may occur nearin time to each other. Additionally, “concurrent” and variations thereofmay or may not mean that two or more events occur at precisely the sametime.

A FDD cell requires spectrum (e.g., radio communication frequencies) inwhich contiguous subsets of the spectrum are entirely allocated toeither UL or DL but not both. Accordingly, FDD may or may not havecarriers that are paired (e.g., may DL than UL carriers). However, TDDmay allocate UL and DL resources on the same carrier frequency.Therefore, TDD may provide more flexibility on spectrum usage. With theincrease in wireless network traffic, and as spectrum resources becomevery precious, new allocated spectrum tends to be fragmented and hassmaller bandwidth, which is more suitable for TDD and/or small celldeployment. Furthermore, TDD may provide flexible channel usage throughtraffic adaptation with different TDD UL-DL configurations and dynamicDL-UL re-configuration.

The systems and methods described herein include carrier aggregation(CA) under the same scheduler control, with a macro cell and a smallcell (e.g., femtocell, picocell, microcell, etc.) heterogeneous networkscenario. For the LTE network deployment, most carriers choose FDD-LTE;however, TDD-LTE is becoming more and more important in many markets. ATDD implementation may provide flexibility for small cells with fasttraffic adaptation.

With TDD CA and hybrid duplexing networks, the macro cells and smallcells may use different frequency bands. A frequency band is a smallsection of the spectrum, in which communication channels may beestablished. For example, in a typical CA case, the macro cell may use alower frequency band and the small cell may use a higher frequency band.For hybrid duplexing networks, a possible combination is to have FDD ona macro cell and TDD on a small cell. Therefore, to allow seamlessoperation, two pairs of association timings are important for CA in ahybrid duplexing network: (1) Physical downlink shared channel (PDSCH)scheduling and PDSCH HARQ-ACK reporting, and (2) Physical uplink sharedchannel (PUSCH) scheduling and PUSCH HARQ-ACK timing.

The PDSCH scheduling and PUSCH scheduling may be performed bycorresponding PDCCH formats. The systems and methods disclosed hereinmay be used for UEs that conform to proposed Rel-11 and future LTEspecifications. For example, a PDCCH or an enhanced PDCCH (ePDCCH) maybe used to schedule PDSCH and/or PUSCH transmissions. The PDSCH HARQ-ACKof CA cells may be reported on a PUCCH or PUSCH of one cell or multiplecells if supported. The PUSCH HARQ-ACK may be signaled on a physicalhybrid automatic repeat request (ARQ) indicator channel (PHICH), a PDCCHor an ePDCCH. For UE conforming to the proposed Rel-11 and future LTEspecifications, the enhanced PDCCH (ePDCCH) and/or enhanced PHICH(ePHICH) may also be used for PUSCH HARQ-ACK feedback.

In one implementation, a PCell may be a macro cell that may beconfigured with FDD, and a SCell may be a small cell (e.g., a picocell)that may be configured with TDD. A hybrid duplex CA may include at leastone cell (or carrier) with FDD, and at least one cell (or carrier) withTDD. This implementation (e.g., a FDD PCell and a TDD SCell) may befurther divided into two cases: self-scheduling and cross-carrierscheduling.

PDSCH scheduling for CA in a hybrid duplexing network may be performedas follows. For PDSCH self-scheduling, the PDSCH transmission on a cellmay be indicated by a corresponding PDCCH (or ePDCCH) on the same cellin the same subframe (e.g., the same transmission time interval (TTI)),or for a PDCCH (or ePDCCH) on the same cell in the same subframeindicating a downlink semi-persistent scheduling (SPS) release. Becauseall PDSCH transmissions may be scheduled on the PDCCH (or ePDCCH) of thesame cell in self-scheduling, the same technique may be used for hybridduplexing networks. In other words, in hybrid duplexing networks,self-scheduling for PDSCH transmission may be performed by acorresponding PDCCH (or ePDCCH) on the same cell in the same subframe.

With cross-carrier scheduling, a PDSCH transmission on a cell may bescheduled by a PDCCH (or an ePDCCH) on another cell. With hybridduplexing networks, if the scheduling cell is a FDD cell and thescheduled cell is a TDD cell, the PDSCH transmission can always becross-carrier scheduled by the FDD scheduling cell. In other words, incross-carrier scheduling, the PDSCH scheduling may follow the schedulingcell timing.

On the other hand, with hybrid duplexing networks, if the schedulingcell is a TDD cell and the scheduled cell is a FDD cell, a PDSCHtransmission may be cross-carrier scheduled with some constraints. Inone implementation, the PDSCH transmission on the scheduled cell may becross-carrier scheduled in the subframes where DL is allocated on thescheduling TDD cell. Therefore, with cross-carrier scheduling, PDSCHscheduling of the scheduled cell may occur in a downlink allocationsubframe of the scheduling cell.

PUSCH scheduling and PUSCH HARQ-ACK may be performed as follows. ForPUSCH self-scheduling, the eNB may schedule a PDCCH (or ePDCCH) with adownlink control information (DCI) format 0/4 and/or a PHICH (or ePHICH)transmission on a serving cell in a DL subframe intended for a UE. TheUE may adjust the corresponding PUSCH transmission in subframe n+k basedon the PDCCH (or ePDCCH) and PHICH (or ePHICH) information, where k maybe 4 for FDD and k may be decided by the TDD UL-DL configurations of theTDD cells. The PUSCH HARQ-ACK report may be associated with the PUSCHtransmission by a PHICH (or ePHICH) or PDCCH (or ePDCCH) on the samecell following the corresponding association timing. Because the PUSCHmay be scheduled on the PDCCH (or ePDCCH) of the same cell inself-scheduling, the same techniques may be used for PUSCH schedulingand PUSCH HARQ-ACK reporting in hybrid duplexing networks.

With cross-carrier scheduling, PUSCH scheduling and PUSCH HARQ-ACKreporting may follow a scheduling cell timing. For example, the PUSCHtransmission on a cell may be scheduled by an UL grant or PHICH (orePHICH) feedback from another cell. With hybrid duplexing networks, ifthe scheduling cell is a FDD cell and the scheduled cell is a TDD cell,the PUSCH transmission may be cross-carrier scheduled.

In one implementation, because UL may be allocated in all subframes ofthe scheduling FDD cell, the scheduled TDD cell may always becross-carrier scheduled with the FDD cell timing on PUSCH scheduling andPUSCH HARQ-ACK reporting. For example, a fixed 4 millisecond (ms) PUSCHscheduling and the feedback association timing of a FDD cell may be usedto cross-carrier schedule a TDD cell.

In another implementation, the PUSCH scheduling and PUSCH HARQ-ACKreporting timing of a TDD cell may be used for the cross-carrierscheduling by a scheduling FDD cell. This approach ensures the samePUSCH scheduling and PUSCH HARQ-ACK timing for both self-scheduling andcross-carrier scheduling cases.

On the other hand, with a hybrid duplexing network in which thescheduling cell is a TDD cell and the scheduled cell is a FDD cell, thePUSCH transmission may be cross-carrier scheduled with some constraints.The scheduled FDD cell may follow the scheduling TDD cell timing onPUSCH scheduling and HARQ-ACK reporting. But the subframes with DLallocation in the TDD scheduling cell may not be able to schedule PUSCHtransmission on the scheduled FDD cell. For example, the FDD cell mayhave a fixed turnaround time of 8 ms for PUSCH scheduling and HARQ-ACKreporting, but all TDD UL-DL configurations have at least 10 msturnaround time. Therefore, the FDD cell timing cannot be applied forPUSCH scheduling and HARQ-ACK reporting for CA in a hybrid duplexingnetwork with cross-carrier scheduling when the scheduling cell is a TDDcell and the scheduled cell is FDD.

Additionally, for CA in a hybrid duplexing network with more than 2cells, a reference cell for PUSCH cross-carrier scheduling and PUSCHHARQ-ACK reporting may be used. For example, if the PCell is a TDD cell,a FDD cell may be configured as a reference cell for PUSCH cross-carrierscheduling and PUSCH HARQ-ACK reporting.

PDSCH HARQ-ACK reporting for CA in a hybrid duplexing network may bescheduled as follows. The PDSCH HARQ-ACK reporting for FDD and TDDnetworks are very different. With FDD, the HARQ-ACK for PDSCHtransmission in subframe n may be reported in subframe n+4 on a PUCCH orPUSCH transmission. However, with TDD, the PDSCH HARQ-ACK may only bereported on subframes with an UL allocation. Therefore, with TDD, an ULsubframe may be associated with more than one DL subframe for PDSCHHARQ-ACK reporting. Accordingly, multi-cell HARQ-ACK reporting for CA inhybrid duplexing networks may be specified.

PDSCH HARQ-ACK reporting for CA in a hybrid duplexing network mayinclude reporting the PDSCH HARQ-ACK information on the PUCCH on onecell only. For example, the PDSCH HARQ-ACK information may be reportedon the PUCCH of the PCell. In Rel-10 and Rel-11, the PUCCH may bereported on the PCell for FDD CA and TDD CA with the same or differentTDD UL-DL configurations. The PUCCH may also be reported on the PCellfor CA in a hybrid duplexing network.

In one implementation, if the PCell is configured with FDD, the FDDPDSCH association timing may be applied to all TDD cells. For example, aTDD cell may follow the timing of a FDD cell in PDSCH HARQ-ACK reportingfor CA in a hybrid duplexing network. Because a DL is available in allsubframes on a FDD cell, the PDSCH HARQ-ACK information on a TDD cellmay always be reported on a corresponding UL of a FDD cell (e.g., aPCell). Therefore, a TDD cell may be treated as a half-duplex FDD cellthat operates on a single frequency carrier instead of separatefrequency carriers for the UL and DL. In other words, the downlinksubframe associations for the TDD cells may follow the PDSCH associationtiming of an FDD cell.

This implementation may be applied regardless of the number of TDD cellsand the TDD UL-DL configurations of the TDD cells. Furthermore, thisimplementation may provide flexible TDD UL-DL reconfiguration withoutchanging of association timings. Therefore, this implementation mayprovide better support for enhanced interference management with trafficadaption (eIMTA).

This approach may provide simple and consistent timing for CA in ahybrid duplexing network that may employ different UL-DL configurations.Furthermore, the PDSCH HARQ-ACK payload may be smaller and more evenlydistributed to all UL subframes. With this implementation, CA in ahybrid duplexing network may be treated as a special case of CA in a FDDnetwork.

For a cross-carrier scheduling case where the scheduling cell isconfigured with FDD and the scheduled cell is configured with TDD, thisimplementation may allow for the scheduling cell timing to be applied onthe scheduled cell. This implementation may also be used forself-scheduling.

Besides the PDSCH HARQ-ACK, the channel state information (CSI) reportsof FDD and TDD cells may also be reported on the PUCCH of the PCellonly. UCI, including CSI and the PDSCH HARQ-ACK, may also be reported onthe PUSCH of an allocated cell with the lowest Cell_ID.

In another implementation, each cell in a hybrid duplexing network mayfollow its own timing. In an UL subframe n, the PDSCH HARQ-ACK bits ofall cells may be generated based on each cell's own association timings.The PDSCH HARQ-ACK bits of all cells may then be multiplexed andreported on the PUCCH on the PCell. In the case where the PUSCH isscheduled in subframe n, the PDSCH HARQ-ACK bits may be multiplexed onthe PUSCH of the cell with the lowest Cell_ID.

If a PCell is configured with FDD, a TDD SCell may maintain its ownPDSCH association timing. For example, in the case where a PCell isconfigured with FDD, an UL subframe is available in every subframe.Therefore, in one implementation of CA in a hybrid duplexing network, aTDD cell following its own PDSCH HARQ-ACK timing may always report thePDSCH HARQ-ACK on an UL on the PCell. In other words, when determining aset of downlink subframe associations for the TDD SCell, the TDD SCellmay maintain the PDSCH association timing of the TDD SCell.

This implementation may be applied even if the hybrid duplexing networkmay include multiple TDD cell with the same or different TDD UL-DLconfigurations. This approach may result in unbalanced PDSCH HARQ-ACKpayload in different UL subframes. In a subframe where a TDD cell isallocated with UL, the PUCCH or PUSCH reporting may carry more HARQ-ACKbits than a subframe where the TDD cell is allocated with DL.

For PDSCH transmissions with self-scheduling, this implementation maymaintain the PDSCH HARQ-ACK timing of each cell. The PDSCH HARQ-ACK bitsmay be multiplexed and reported on the PUCCH on the PCell. Forcross-carrier scheduling, this implementation may also be applied. Inone case, a scheduling cell PDSCH HARQ-ACK timing may be used for PDSCHtransmissions with cross-carrier scheduling. In another case, thescheduled cell PDSCH HARQ-ACK timing may be used for PDSCH transmissionswith cross-carrier scheduling.

In yet another implementation of PDSCH HARQ-ACK reporting for CA in ahybrid duplexing network, a reporting cell may be used if a PCell is aTDD cell. It should be noted that the macro cell and small cellconfiguration does not necessarily mean the PCell is the macro cell andSCell is a small cell. In some cases, the PCell may be the small celland the SCell may be the macro cell. Therefore, though the systems andmethods above are discussed mainly for the case where a PCell may beconfigured with FDD and a SCell may be configured with TDD, in anotherimplementation, the PCell may be configured with TDD and the SCell maybe configured with FDD.

FDD timing is simple and consistent, compared with TDD timing, which isdifferent for different TDD UL-DL configurations that may appear in aset of small cells affiliated with, or spatially relevant with, an areaassociated with a larger cell. Therefore, it may be better to use a FDD(larger) cell to report the UCI (e.g., PDSCH HARQ-ACK and CSI).Therefore, for CA in a hybrid duplexing network, a FDD cell may beconfigured as a PDSCH HARQ-ACK reporting cell (also denoted as areference cell) even if the PCell is a TDD cell. In other words, thePDSCH HARQ-ACK reporting may be on a SCell that is configured with FDD.The PDSCH HARQ-ACK reporting cell or reference cell may be the UCIreporting cell (e.g., the UCI transmission cell) or reference cell sothat all UCI is reported on the UCI reporting cell. The UCI may includeHARQ-ACK and channel state information (CSI). The CSI may includechannel quality indicator (CQI) and/or rank indication (RI) and/orprecoding matrix indicator (PMI) and/or precoding type indicator (PTI)etc.

In another implementation, a PDSCH HARQ-ACK reporting cell or UCIreporting cell may be implicitly decided as the FDD cell with the lowestCell_ID. Additionally, the PDSCH HARQ-ACK reporting cell or UCIreporting cell may be configured by physical (PHY) layer signaling(e.g., in the synchronization, broadcasting signals, system informationblock (SIB) 1 and/or SIB messages). Furthermore, the PDSCH HARQ-ACKreporting cell or UCI reporting cell may be configured by higher layersignaling (e.g., radio resource control (RRC) signaling). Therefore, thePDSCH HARQ-ACK of all cells may be reported on the PUCCH or PUSCH of theconfigured reporting cell.

PDSCH HARQ-ACK reporting for CA in a hybrid duplexing network may alsobe separate and independent for FDD cells and TDD cells. In other words,cells for each duplex may maintain independent PUCCH and/or PUSCHreports.

TDD and FDD systems have very different PDSCH HARQ-ACK associationtimings. Also, there are considerable differences on the PDCCH (orePDCCH) formats and CSI estimation and reports. Therefore, in animplementation of CA in a hybrid duplexing network, the FDD cells andTDD cells may maintain separate and independent PDSCH HARQ-ACK reportingand CSI feedback mechanisms. For example, one FDD cell may be configuredas the PCell (or anchor cell) for all FDD cells, and one TDD cell may beconfigured as the PCell (or anchor cell) for all TDD cells. The FDDcells may perform CA as in Rel-10/11, and the TDD cells may perform CAas in Rel-10 if all TDD cells have the same TDD UL-DL configuration orthe TDD cells may perform CA as in Rel-11 if different TDD UL-DLconfigurations are used in the TDD cells. Therefore, if the PCell is amacro cell with FDD and the SCell is a small cell with TDD, the smallcell may perform PUCCH reporting that is separate and independent fromthe macro cell.

In a hybrid duplexing network, the PCell may be a FDD cell or a TDDcell. The FDD PCell and the TDD PCell may be the PCell or a SCellconfigured to perform CA in a hybrid duplexing network. The FDD PCellmay also be configured as a FDD anchor cell. Furthermore, the TDD PCellmay also be configured as a TDD anchor cell. The FDD PCell (or FDDanchor cell) or the TDD PCell (or TDD anchor cell) may be the PCell orthe secondary PCell.

Therefore, a PUCCH on the FDD PCell may be used to report PDSCH HARQ-ACKfor all FDD cells, and a PUCCH on the TDD PCell may be used to reportPDSCH HARQ-ACK information for all TDD cells. Therefore, in CA withhybrid duplexing networks, PUCCH reporting on a SCell may be supported,where the given SCell may operate as an anchor cell or secondary PCell.

In a subframe where UCI (e.g., PDSCH HARQ-ACK information and/or CSI) isreported for the FDD cells only, the UCI may be reported on the PUCCH ofthe FDD PCell. In a subframe where UCI (e.g., PDSCH HARQ-ACK informationand/or CSI) is reported for the TDD cells only, the UCI may be reportedon the PUCCH of the TDD PCell.

Two implementations may be used to report PDSCH HARQ-ACK bits on bothFDD cells and TDD cells in the same subframe. In one implementation,multiple PUCCHs may be reported simultaneously on the FDD PCell (or FDDanchor cell) and the TDD PCell (or TDD anchor cell). In anotherimplementation, only one PUCCH may be reported, and the PDSCH HARQ-ACKbits of both the FDD and TDD cells may be multiplexed and reported onthe PUCCH of the PCell only.

With independent reporting for FDD and TDD cells, the PDSCH HARQ-ACKinformation or CSI may also be reported on a PUSCH. In oneimplementation, the PDSCH HARQ-ACK information and CSI of all FDD cellsmay be reported on an allocated PUSCH of the FDD cell with the lowestCell_ID. The PDSCH HARQ-ACK information and/or CSI of all TDD cells mayalso be reported on an allocated PUSCH of the TDD cell with the lowestCell_ID. In another implementation, the PDSCH HARQ-ACK informationand/or CSI reporting for FDD cells and the PDSCH HARQ-ACK informationand/or CSI reporting for TDD cells may use different channel formats.For example, the PDSCH HARQ-ACK information and CSI of FDD cells may bereported on a PUCCH and the PDSCH HARQ-ACK information and CSI of TDDcells may be reported on a PUSCH, and vice versa. In yet anotherimplementation, the PDSCH HARQ-ACK information and CSI of all FDD andTDD cells may be multiplexed together and reported on the allocatedPUSCH of the cell with the lowest Cell_ID.

It should be noted that independent reporting (on PUCCH or PUSCH) by FDDand TDD cells may be used if the PCell is configured with either FDD orTDD. Furthermore, it should be noted that independent reporting (onPUCCH or PUSCH) by FDD and TDD cells may be applied to bothself-scheduling and cross-carrier scheduling.

The systems and methods disclosed herein may provide the followingbenefits. CA in a hybrid duplexing network that includes FDD and TDDcells may operate seamlessly. Resource use may be flexible when both FDDand TDD are used by a UE. HARQ-ACK reporting methods may support thedynamic UL-DL reconfiguration of TDD cells. Independent uplink controlinformation (UCI) reporting on a PUCCH or a PUSCH may be performed bycarriers with different duplexing methods. Standalone operations forcarriers with different duplexing methods may be supported. The use of aFDD cell timing on a TDD cell in a hybrid CA scenario may be supported.Additionally, a reporting cell (or reference cell) implementation byphysical (PHY) layer signaling, implicit signaling and/or higher layersignaling may be supported.

Various examples of the systems and methods disclosed herein are nowdescribed with reference to the Figures, where like reference numbersmay indicate functionally similar elements. The systems and methods asgenerally described and illustrated in the Figures herein could bearranged and designed in a wide variety of different implementations.Thus, the following more detailed description of severalimplementations, as represented in the Figures, is not intended to limitscope, as claimed, but is merely representative of the systems andmethods.

FIG. 1 is a block diagram illustrating one configuration of one or moreeNBs 160 and one or more UEs 102 in which systems and methods forcarrier aggregation may be implemented. The one or more UEs 102communicate with one or more eNBs 160 using one or more antennas 122a-n. For example, a UE 102 transmits electromagnetic signals to the eNB160 and receives electromagnetic signals from the eNB 160 using the oneor more antennas 122 a-n. The eNB 160 communicates with the UE 102 usingone or more antennas 180 a-n.

The UE 102 and the eNB 160 may use one or more channels 119, 121 tocommunicate with each other. For example, a UE 102 may transmitinformation or data to the eNB 160 using one or more uplink channels121. Examples of uplink channels 121 include a PUCCH and a PUSCH, etc.The one or more eNBs 160 may also transmit information or data to theone or more UEs 102 using one or more downlink channels 119, forinstance. Examples of downlink channels 119 include a PDCCH, a PDSCH,etc. Other kinds of channels may be used.

Each of the one or more UEs 102 may include one or more transceivers118, one or more demodulators 114, one or more decoders 108, one or moreencoders 150, one or more modulators 154, a data buffer 104 and a UEoperations module 124. For example, one or more reception and/ortransmission paths may be implemented in the UE 102. For convenience,only a single transceiver 118, decoder 108, demodulator 114, encoder 150and modulator 154 are illustrated in the UE 102, though multipleparallel elements (e.g., transceivers 118, decoders 108, demodulators114, encoders 150 and modulators 154) may be implemented.

The transceiver 118 may include one or more receivers 120 and one ormore transmitters 158. The one or more receivers 120 may receive signalsfrom the eNB 160 using one or more antennas 122 a-n. For example, thereceiver 120 may receive and downconvert signals to produce one or morereceived signals 116. The one or more received signals 116 may beprovided to a demodulator 114. The one or more transmitters 158 maytransmit signals to the eNB 160 using one or more antennas 122 a-n. Forexample, the one or more transmitters 158 may upconvert and transmit oneor more modulated signals 156.

The demodulator 114 may demodulate the one or more received signals 116to produce one or more demodulated signals 112. The one or moredemodulated signals 112 may be provided to the decoder 108. The UE 102may use the decoder 108 to decode signals. The decoder 108 may produceone or more decoded signals 106, 110. For example, a first UE-decodedsignal 106 may comprise received payload data, which may be stored in adata buffer 104. A second UE-decoded signal 110 may comprise overheaddata and/or control data. For example, the second UE-decoded signal 110may provide data that may be used by the UE operations module 124 toperform one or more operations.

As used herein, the term “module” may mean that a particular element orcomponent may be implemented in hardware, software or a combination ofhardware and software. However, it should be noted that any elementdenoted as a “module” herein may alternatively be implemented inhardware. For example, the UE operations module 124 may be implementedin hardware, software or a combination of both.

In general, the UE operations module 124 may enable the UE 102 tocommunicate with the one or more eNBs 160. The UE operations module 124may include one or more of a UE UCI transmission cell determinationmodule 126, a UE first cell selection module 128, a UE downlink subframeassociations determination module 130 and a UE PDSCH HARQ-ACK module132.

The UE UCI transmission cell determination module 126 may determine acell that may transmit UCI information between the UE 102 and the eNB160. Examples of UCI include PDSCH HARQ-ACK information and CSI. The UCItransmission cell may be either a FDD cell or a TDD cell. Therefore, theUE UCI transmission cell determination module 126 may determine a UCItransmission cell that is either a FDD or a TDD cell. In oneimplementation, the UE UCI transmission cell determination module 126may select which cell may be the UCI transmission cell. In anotherimplementation, the UE UCI transmission cell determination module 126may be instructed (by the eNB 160, for example) which cell to use forthe UCI transmission. For example, the UE 102 may receive an indicatorfrom the eNB 160 that indicates one or more cells for UCI transmission.Accordingly, the UE UCI transmission cell determination module 126 maydetermine one or more cells for UCI transmission based on (e.g.,indicated by) the indicator. The UCI transmission cell may include acommunication channel 119, 121 between the UE 102 and an eNB 160 fortransmitting UCI.

In one implementation, the UE UCI transmission cell determination module126 may determine that the UCI transmission cell is a FDD cell. In oneexample, the UE UCI transmission cell determination module 126 maydetermine that the UCI transmission cell is a PCell configured with FDD.In this example, the UCI may be sent on one cell only (e.g., a PCell)for all of the CA cells (e.g., the FDD cell(s) and TDD cell(s)) in thehybrid duplexing network.

In another implementation, the UE UCI transmission cell determinationmodule 126 may determine that the UCI transmission cell is a FDDreporting cell. For example, the PCell may be a TDD cell, and the UCItransmission cell may be a reporting cell configured with FDD.

In yet another implementation, the UE UCI transmission celldetermination module 126 may determine a UCI transmission cell and asecond UCI transmission cell that utilize different duplexing. Forexample, the UE UCI transmission cell determination module 126 maydetermine a UCI transmission cell for one or more FDD cells, and the UEUCI transmission cell determination module 126 may also determine aseparate second UCI transmission cell for one or more TDD cells. In thisimplementation, the UCI transmission cell for the FDD cells may be a FDDanchor cell, and the second UCI transmission cell for the TDD cells maybe a TDD anchor cell.

The UE first cell selection module 128 may select a cell for FDD and TDDcarrier aggregation. In one implementation, the UE first cell selectionmodule 128 may select a TDD cell that may be included with the UCItransmission cell in performing CA. Alternatively, the UE first cellselection module 128 may select a FDD cell that may be included with theUCI transmission cell in performing CA. In some implementations, the UEfirst cell selection module 128 may determine the cell for FDD and TDDcarrier aggregation based on an indicator (from the eNB 160) thatindicates the cell for FDD and TDD carrier aggregation.

The UE downlink subframe associations determination module 130 maydetermine a set of downlink subframe associations for the first cellthat indicate at least one UCI transmission uplink subframe of the UCItransmission cell. The set of downlink subframe associations may includetimings (e.g., PDSCH HARQ-ACK associations) that correspond to a UCItransmission uplink subframe. In some implementations, the UE downlinksubframe associations determination module 130 may determine the set ofdownlink subframe associations based on an indicator (from the eNB 160)that indicates the set of downlink subframe associations.

In one implementation, the UE downlink subframe associationsdetermination module 130 may determine that the set of downlinkassociations for the first cell may include the PDSCH association timingof the UCI transmission cell. For example, if the UCI transmission cellis a FDD cell and the first cell is a TDD cell, the first cell mayfollow the association timing of a FDD cell.

In another implementation, the UE downlink subframe associationsdetermination module 130 may determine that the set of downlink subframeassociations for first cell may include maintaining the PDSCHassociation timing of the first cell. For example, if the UCItransmission cell is a FDD cell and the first cell is a TDD cell, thefirst cell may maintain its own PDSCH association timing. Therefore, thefirst cell may use a TDD UL-DL configuration as described below inconnection with FIG. 5 and FIG. 6.

The UE PDSCH HARQ-ACK module 132 may send PDSCH HARQ-ACK information inthe UCI transmission uplink subframe of the UCI transmission cell. Forexample, the UE PDSCH HARQ-ACK module 132 may send PDSCH HARQ-ACKinformation in the UCI transmission uplink subframe corresponding to theset of downlink subframe associations. For instance, the UE PDSCHHARQ-ACK module 132 may inform the transmitter(s) 158 when or when notto send PDSCH HARQ-ACK information based on the set of downlink subframeassociations.

In one implementation, the UE PDSCH HARQ-ACK module 132 may send PDSCHHARQ-ACK information on the PUCCH or PUSCH of one cell only. Forexample, the UE PDSCH HARQ-ACK module 132 may send PDSCH HARQ-ACKinformation for all cells (including the first cell) on the PUCCH of aUCI transmission cell that is a FDD cell.

In another implementation, the UE PDSCH HARQ-ACK module 132 may sendPDSCH HARQ-ACK information to multiple cells. For example, where the FDDand TDD cells may have separate UCI transmission cells, the UE PDSCHHARQ-ACK module 132 may concurrently send PDSCH HARQ-ACK information ina UCI transmission uplink subframe to the UCI transmission cell for theFDD cells and to the second UCI transmission cell for the TDD cells. Inother words, PDSCH HARQ-ACK information for the FDD cells may be sent bythe UCI transmission cell and the PDSCH HARQ-ACK information for the TDDcells may be sent by the second UCI transmission cell.

The UE operations module 124 may provide information 148 to the one ormore receivers 120. For example, the UE operations module 124 may informthe receiver(s) 120 when to receive retransmissions.

The UE operations module 124 may provide information 138 to thedemodulator 114. For example, the UE operations module 124 may informthe demodulator 114 of a modulation pattern anticipated fortransmissions from the eNB 160.

The UE operations module 124 may provide information 136 to the decoder108. For example, the UE operations module 124 may inform the decoder108 of an anticipated encoding for transmissions from the eNB 160.

The UE operations module 124 may provide information 142 to the encoder150. The information 142 may include data to be encoded and/orinstructions for encoding. For example, the UE operations module 124 mayinstruct the encoder 150 to encode transmission data 146 and/or otherinformation 142. The other information 142 may include PDSCH HARQ-ACKinformation.

The encoder 150 may encode transmission data 146 and/or otherinformation 142 provided by the UE operations module 124. For example,encoding the data 146 and/or other information 142 may involve errordetection and/or correction coding, mapping data to space, time and/orfrequency resources for transmission, multiplexing, etc. The encoder 150may provide encoded data 152 to the modulator 154.

The UE operations module 124 may provide information 144 to themodulator 154. For example, the UE operations module 124 may inform themodulator 154 of a modulation type (e.g., constellation mapping) to beused for transmissions to the eNB 160. The modulator 154 may modulatethe encoded data 152 to provide one or more modulated signals 156 to theone or more transmitters 158.

The UE operations module 124 may provide information 140 to the one ormore transmitters 158. This information 140 may include instructions forthe one or more transmitters 158. For example, the UE operations module124 may instruct the one or more transmitters 158 when to transmit asignal to the eNB 160. In some configurations, this may be based on theUE downlink subframe associations determination module 130 (based on aUL-DL configuration, for example). For instance, the one or moretransmitters 158 may transmit during an UL subframe. The one or moretransmitters 158 may upconvert and transmit the modulated signal(s) 156to one or more eNBs 160.

The eNB 160 may include one or more transceivers 176, one or moredemodulators 172, one or more decoders 166, one or more encoders 109,one or more modulators 113, a data buffer 162 and an eNB operationsmodule 182. For example, one or more reception and/or transmission pathsmay be implemented in an eNB 160. For convenience, only a singletransceiver 176, decoder 166, demodulator 172, encoder 109 and modulator113 are illustrated in the eNB 160, though multiple parallel elements(e.g., transceivers 176, decoders 166, demodulators 172, encoders 109and modulators 113) may be implemented.

The transceiver 176 may include one or more receivers 178 and one ormore transmitters 117. The one or more receivers 178 may receive signalsfrom the UE 102 using one or more antennas 180 a-n. For example, thereceiver 178 may receive and downconvert signals to produce one or morereceived signals 174. The one or more received signals 174 may beprovided to a demodulator 172. The one or more transmitters 117 maytransmit signals to the UE 102 using one or more antennas 180 a-n. Forexample, the one or more transmitters 117 may upconvert and transmit oneor more modulated signals 115.

The demodulator 172 may demodulate the one or more received signals 174to produce one or more demodulated signals 170. The one or moredemodulated signals 170 may be provided to the decoder 166. The eNB 160may use the decoder 166 to decode signals. The decoder 166 may produceone or more decoded signals 164, 168. For example, a first eNB-decodedsignal 164 may comprise received payload data, which may be stored in adata buffer 162. A second eNB-decoded signal 168 may comprise overheaddata and/or control data. For example, the second eNB-decoded signal 168may provide data (e.g., PDSCH HARQ-ACK information) that may be used bythe eNB operations module 182 to perform one or more operations.

In general, the eNB operations module 182 may enable the eNB 160 tocommunicate with the one or more UEs 102. The eNB operations module 182may include one or more of eNB UCI transmission cell determinationmodule 194, an eNB first cell selection module 196, an eNB downlinksubframe associations determination module 198 and an eNB PDSCH HARQ-ACKmodule 107.

The eNB UCI transmission cell determination module 194 may determine acell that may transmit UCI information between the UE 102 and the eNB160. Examples of UCI include PDSCH HARQ-ACK and CSI. The UCItransmission cell may be either a FDD cell or a TDD cell. Therefore, theeNB UCI transmission cell determination module 194 may determine a UCItransmission cell that is either a FDD or a TDD cell. In oneimplementation, the eNB UCI transmission cell determination module 194may select which cell may be the UCI transmission cell. In anotherimplementation, the eNB UCI transmission cell determination module 194may instruct (the UE 102, for example) which cell is the UCItransmission cell. For example, the eNB UCI transmission celldetermination module 194 may generate and send an indicator thatindicates one or more cells for UCI transmission. The UCI transmissioncell may include a communication channel 119, 121 between the UE 102 andan eNB 160 for transmitting UCI.

In one implementation, the eNB UCI transmission cell determinationmodule 194 may determine that the UCI transmission cell is a FDD cell.Additionally, the eNB UCI transmission cell determination module 194 maydetermine that the UCI transmission cell is a PCell configured with FDD.In this implementation, the UCI may be received on one cell only (e.g.,a PCell) for all of the CA cells (e.g., the FDD cells and TDD cells) inthe hybrid duplexing network.

In another implementation, the eNB UCI transmission cell determinationmodule 194 may determine that the UCI transmission cell is a FDDreporting cell. For example, the PCell may be a TDD cell, and the UCItransmission cell may be a reporting cell configured with FDD.

In yet another implementation, the eNB UCI transmission celldetermination module 194 may determine a UCI transmission cell and asecond UCI transmission cell that utilize different duplexing. Forexample, the eNB UCI transmission cell determination module 194 maydetermine a UCI transmission cell for one or more FDD cells, and the eNBUCI transmission cell determination module 194 may also determine aseparate second UCI transmission cell for one or more TDD cells. In thisimplementation, the UCI transmission cell for the FDD cells may be a FDDanchor cell, and the second UCI transmission cell for the TDD cells maybe a TDD anchor cell.

The eNB first cell selection module 196 may select a cell for FDD andTDD carrier aggregation. In one implementation, the eNB first cellselection module 196 may select a TDD cell that may be included with theUCI transmission cell in performing CA. Alternatively, the eNB firstcell selection module 196 may select a FDD cell that may be includedwith the UCI transmission cell in performing CA. In someimplementations, the eNB first cell selection module 196 may generateand send an indicator (to a UE 102) that indicates the cell for FDD andTDD carrier aggregation.

The eNB downlink subframe associations determination module 198 maydetermine a set of downlink subframe associations for the first cellthat indicate at least one UCI transmission uplink subframe of the UCItransmission cell. The set of downlink subframe associations may includetimings (e.g., PDSCH HARQ-ACK associations) that correspond to a UCItransmission uplink subframe. In some implementations, the eNB downlinksubframe associations determination module 198 may generate and send anindicator (to a UE 102) that indicates the set of downlink subframeassociations.

In one implementation, the eNB downlink subframe associationsdetermination module 198 may determine that the set of downlinkassociations for the first cell may include the PDSCH association timingof the UCI transmission cell. For example, if the UCI transmission cellis a FDD cell and the first cell is a TDD cell, the first cell mayfollow the association timing of a FDD cell.

In another implementation, the eNB downlink subframe associationsdetermination module 198 may determine that the set of downlink subframeassociations for the first cell may include maintaining the PDSCHassociation timing of the first cell. For example, if the UCItransmission cell is a FDD cell and the first cell is a TDD cell, thefirst cell may maintain its own PDSCH association timing. Therefore, thefirst cell may use a TDD UL-DL configuration as described below inconnection with FIG. 5 and FIG. 6.

The eNB PDSCH HARQ-ACK module 107 may receive PDSCH HARQ-ACK informationin the UCI transmission uplink subframe of the UCI transmission cell.For example, the eNB PDSCH HARQ-ACK module 107 may receive PDSCHHARQ-ACK information in the UCI transmission uplink subframecorresponding to the set of downlink subframe associations. Forinstance, the eNB PDSCH HARQ-ACK module 107 may inform the receivers(s)178 when or when not to receive PDSCH HARQ-ACK information based on theset of downlink subframe associations.

In one implementation, the eNB PDSCH HARQ-ACK module 107 may receivePDSCH HARQ-ACK information on the PUCCH or PUSCH of one cell only. Forexample, the eNB PDSCH HARQ-ACK module 107 may receive PDSCH HARQ-ACKinformation for all cells (including the first cell) on the PUCCH of aUCI transmission cell that is a FDD cell.

In another implementation, the eNB PDSCH HARQ-ACK module 107 may receivePDSCH HARQ-ACK information on multiple cells. For example, where the FDDand TDD cells may have separate UCI transmission cells, the eNB PDSCHHARQ-ACK module 107 may concurrently receive PDSCH HARQ-ACK informationin a UCI transmission uplink subframe on the UCI transmission cell forthe FDD cells and/or on the second UCI transmission cell for the TDDcells.

The eNB operations module 182 may provide information 190 to the one ormore receivers 178. For example, the eNB operations module 182 mayinform the receiver(s) 178 when or when not to receive PDSCH HARQ-ACKinformation based on the set of downlink subframe associations.

The eNB operations module 182 may provide information 188 to thedemodulator 172. For example, the eNB operations module 182 may informthe demodulator 172 of a modulation pattern anticipated fortransmissions from the UE(s) 102.

The eNB operations module 182 may provide information 186 to the decoder166. For example, the eNB operations module 182 may inform the decoder166 of an anticipated encoding for transmissions from the UE(s) 102.

The eNB operations module 182 may provide information 101 to the encoder109. The information 101 may include data to be encoded and/orinstructions for encoding. For example, the eNB operations module 182may instruct the encoder 109 to encode transmission data 105 and/orother information 101.

The encoder 109 may encode transmission data 105 and/or otherinformation 101 provided by the eNB operations module 182. For example,encoding the data 105 and/or other information 101 may involve errordetection and/or correction coding, mapping data to space, time and/orfrequency resources for transmission, multiplexing, etc. The encoder 109may provide encoded data 111 to the modulator 113. The transmission data105 may include network data to be relayed to the UE 102.

The eNB operations module 182 may provide information 103 to themodulator 113. This information 103 may include instructions for themodulator 113. For example, the eNB operations module 182 may inform themodulator 113 of a modulation type (e.g., constellation mapping) to beused for transmissions to the UE(s) 102. The modulator 113 may modulatethe encoded data 111 to provide one or more modulated signals 115 to theone or more transmitters 117.

The eNB operations module 182 may provide information 192 to the one ormore transmitters 117. This information 192 may include instructions forthe one or more transmitters 117. For example, the eNB operations module182 may instruct the one or more transmitters 117 when to (or when notto) transmit a signal to the UE(s) 102. In some implementations, thismay be based on an UL-DL configuration. The one or more transmitters 117may upconvert and transmit the modulated signal(s) 115 to one or moreUEs 102.

It should be noted that a DL subframe may be transmitted from the eNB160 to one or more UEs 102 and that an UL subframe may be transmittedfrom one or more UEs 102 to the eNB 160. Furthermore, both the eNB 160and the one or more UEs 102 may transmit data in a standard specialsubframe.

It should also be noted that one or more of the elements or partsthereof included in the eNB(s) 160 and UE(s) 102 may be implemented inhardware. For example, one or more of these elements or parts thereofmay be implemented as a chip, circuitry or hardware components, etc. Itshould also be noted that one or more of the functions or methodsdescribed herein may be implemented in and/or performed using hardware.For example, one or more of the methods described herein may beimplemented in and/or realized using a chipset, an application-specificintegrated circuit (ASIC), a large-scale integrated circuit (LSI) orintegrated circuit, etc.

FIG. 2 is a flow diagram illustrating one implementation of a method 200for performing carrier aggregation by a UE 102. A UE 102 may determine202 a UCI transmission cell in a wireless communication network with atleast one FDD cell and at least one TDD cell. For example, the wirelesscommunication network may be a hybrid duplexing network in which carrieraggregation may be performed with one or more FDD cells and one or moreTDD cells. Additionally, in one implementation, the wirelesscommunication network may be an LTE network. UCI may include one or moreof PDSCH HARQ-ACK information and CSI. The UCI transmission cell mayinclude a communication channel 119, 121 between the UE 102 and an eNB160 for transmitting UCI. The UCI transmission cell may be either a FDDcell or a TDD cell. Therefore, the UE 102 may determine 202 a UCItransmission cell that is either a FDD or a TDD cell. In someimplementations, the UE 102 may make this determination 202 based on anindicator received from an eNB 160 that indicates the UCI transmissioncell.

In one implementation, the UE may determine 202 that the UCItransmission cell is a FDD cell. For example, the UCI transmission cellmay be a PCell, which may be a macro cell that is configured with FDD.In this implementation, the UCI may be reported on one cell only (e.g.,a PCell) for all of the cells (e.g., the FDD cells and TDD cells) in thehybrid duplexing network. The UCI may be reported on a PUCCH of thePCell. Alternatively, the UCI may be reported on the PUSCH of theallocated cell with the lowest Cell_ID.

In another implementation, the UE may determine 202 that the UCItransmission cell is a FDD reporting cell. For example, the PCell may bea TDD cell, but the UCI transmission cell may be determined 202 to be areporting cell configured with FDD. Therefore, in this implementation,the UCI transmission cell may be a SCell that is configured with FDD.

In yet another implementation, the UE 102 may determine 202 a UCItransmission cell for FDD cells, and the UE 102 may also determine 202 aseparate second UCI transmission cell for TDD cells. For example, theFDD cells and TDD cells may maintain independent UCI reports. In thisimplementation, the UE 102 may determine 202 that a FDD anchor cell maybe the UCI transmission cell for the FDD cells. The FDD anchor cell maybe a PCell, SCell or a secondary PCell. The UE 102 may also determine202 that a TDD anchor cell may be the second UCI transmission cell forthe TDD cells. The TDD anchor cell may be a PCell, SCell or a secondaryPCell.

The UE 102 may select 204 a first cell for FDD and TDD carrieraggregation. For example, the UE 102 may select 204 a FDD cell or a TDDcell as a first cell for carrier aggregation. The first cell may be aPCell or a SCell. Additionally, the first cell may be the same cell asthe UCI transmission cell, or the first cell may be a different cellthan the UCI transmission cell. In some implementations, the UE 102 maymake this selection 204 based on an indicator received from an eNB 160that indicates the first cell for FDD and TDD carrier aggregation.

The UE 102 may determine 206 a set of downlink subframe associations forthe first cell that indicate at least one UCI transmission uplinksubframe of the UCI transmission cell. The set of downlink subframeassociations may include timings (e.g., PDSCH HARQ-ACK associations) forat least one corresponding UCI transmission uplink subframe, asdescribed below in connection with FIG. 5, FIG. 6 and FIG. 7. In someimplementations, the UE 102 may make this determination 206 based on anindicator received from an eNB 160 that indicates the set of downlinksubframe associations.

In one implementation, the UE 102 may determine 206 that the set ofdownlink associations for the first cell may include the PDSCHassociation timing of the UCI transmission cell. For example, if the UCItransmission cell is a FDD cell and the first cell is a TDD cell, thefirst cell may follow the association timing of a FDD cell. In otherwords, if the first cell is a TDD cell, the first cell may follow theassociation timing of a FDD cell in PDSCH HARQ-ACK reporting for CA in ahybrid duplexing network.

In another implementation, the UE 102 may determine 206 that the set ofdownlink subframe associations for first cell may include maintaining aPDSCH association timing of the first cell. For example, if the UCItransmission cell is a FDD cell and the first cell is a TDD cell, thefirst cell may maintain its own PDSCH association timing. For instance,the first cell may use a TDD UL-DL configuration as described below inconnection with FIG. 5 and FIG. 6.

In this implementation, the PDSCH HARQ-ACK bits of the first cell may bemultiplexed and reported on the PUCCH or PUSCH on the UCI transmissioncell. Alternatively, the FDD cells and the TDD cells may maintainindependent reporting mechanisms with their own PDSCH associationtimings.

The UE 102 may send 208 PDSCH HARQ-ACK information in the UCItransmission uplink subframe of the UCI transmission cell. For example,the UE 102 may send 208 PDSCH HARQ-ACK information in the UCItransmission uplink subframe corresponding to the determined 206 set ofdownlink subframe associations.

In one implementation, the UE 102 may send 208 PDSCH HARQ-ACKinformation on the PUCCH or PUSCH of one cell only. For example, if theUCI transmission cell is a FDD cell, the first cell is a TDD, and theset of downlink subframe associations for the first cell includes thePDSCH association timing of the UCI transmission cell, the UE 102 maysend 208 PDSCH HARQ-ACK information for the TDD cell in an UL (e.g.,PUCCH or PUSCH) of the FDD cell. Because a DL is available in allsubframes on a FDD cell, the PDSCH HARQ-ACK on a TDD cell may always bereported on a corresponding UL of a FDD cell.

In another implementation where the UCI transmission cell is a FDD cell,the first cell is a TDD, but the set of downlink subframe associationsfor the first cell may include maintaining the PDSCH association timingof the first cell, the UE 102 may also send 208 PDSCH HARQ-ACKinformation on the PUCCH or PUSCH of one cell only. In thisimplementation, the PDSCH HARQ-ACK information for each cell may begenerated based on its own association timings. For example, a TDD cellmay follow a TDD DL-UL configuration as described in connection withFIG. 5, and a FDD cell may follow an association timing as described inconnection with FIG. 7. Therefore, PDSCH HARQ-ACK information for thefirst cell may be generated according to the association timing of thefirst cell. Additionally, the PDSCH HARQ-ACK information for the firstcell may be multiplexed and sent 208 by the UE 102 in the UCItransmission uplink subframe of the UCI transmission cell. In otherwords, the UE 102 may send 208 PDSCH HARQ-ACK information for the TDDcell in an UL (e.g., PUCCH or PUSCH) of the FDD cell.

In yet another implementation, where the FDD cells may have a UCItransmission cell and the TDD cells may have a second UCI transmissioncell, the UE 102 may send 208 PDSCH HARQ-ACK information in a UCItransmission uplink subframe to one or more cells. For example, asdescribed above, the FDD cells and TDD cells may maintain independentUCI reports. In this case, the FDD cells may include a UCI transmissioncell (e.g., a FDD anchor cell) and the TDD cells may include a secondUCI transmission cell (e.g., a TDD anchor cell). Multiple PUCCHs orPUSCHs may be reported concurrently on the FDD anchor cell and the TDDanchor cell. The UE 102 may concurrently send 208 PDSCH HARQ-ACKinformation for the FDD cells and TDD cells in a UCI transmission uplinksubframe corresponding to the UCI transmission cell or the second UCItransmission cell. Alternatively, the PDSCH HARQ-ACK information forboth the FDD cells and the TDD cells may be multiplexed and sent 208 inan UL (e.g., PUCCH or PUSCH) of one cell (e.g., a PCell).

FIG. 3 is a flow diagram illustrating one implementation of a method 300for performing carrier aggregation by an eNB 160. An eNB 160 maydetermine 302 a UCI transmission cell in a wireless communicationnetwork with at least one FDD cell and at least one TDD cell. Forexample, the wireless communication network may be a hybrid duplexingnetwork in which carrier aggregation may be performed with one or moreFDD cell and one or more TDD cell. Additionally, in one implementation,the wireless communication network may be an LTE network. UCI mayinclude one or more of PDSCH HARQ-ACK information and CSI. The UCItransmission cell may include a communication channel 119, 121 betweenthe eNB 160 and a UE 102 for transmitting UCI. The UCI transmission cellmay be either a FDD cell or a TDD cell. Therefore, the eNB 160 maydetermine 302 a UCI transmission cell that is either a FDD or a TDDcell. In some implementations, the eNB 160 may generate and send anindicator based on this determination 302 that indicates the UCItransmission cell.

In one implementation, the UE may determine 302 that the UCItransmission cell is a FDD cell. For example, the UCI transmission cellmay be a PCell, which may be a macro cell that is configured with FDD.In this implementation, the UCI may be reported on one cell only (e.g.,a PCell) for all of the cells (e.g., the FDD cells and TDD cells) in thehybrid duplexing network. The UCI may be reported on a PUCCH of thePCell. Alternatively, the UCI may be reported on the PUSCH of theallocated cell with the lowest Cell_ID.

In another implementation, the UE may determine 302 that the UCItransmission cell is a FDD reporting cell. For example, the PCell may bea TDD cell, but the UCI transmission cell may be determined 302 to be areporting cell configured with FDD. Therefore, in this implementation,the UCI transmission cell may be an SCell that is configured with FDD.

In yet another implementation, the eNB 160 may determine 302 a UCItransmission cell for FDD cells, and the eNB 160 may also determine 302a separate second UCI transmission cell for TDD cells. For example, theFDD cells and TDD cells may maintain independent UCI reports. In thisimplementation, the eNB 160 may determine 302 that a FDD anchor cell maybe the UCI transmission cell for the FDD cells. The FDD anchor cell maybe a PCell, SCell or a secondary PCell. The eNB 160 may also determine302 that a TDD anchor cell may be the second UCI transmission cell forthe TDD cells. The TDD anchor cell may be a PCell, SCell or a secondaryPCell.

The eNB 160 may select 304 a first cell for FDD and TDD carrieraggregation. For example, the eNB 160 may select 304 a FDD cell or a TDDcell as a first cell for carrier aggregation. The first cell may be aPCell or an SCell. In some implementations, the eNB 160 may generate andsend an indicator based on this selection 304 that indicates the firstcell for FDD and TDD carrier aggregation.

The eNB 160 may determine 306 a set of downlink subframe associationsfor the first cell that indicate at least one UCI transmission uplinksubframe of the UCI transmission cell. The set of downlink subframeassociations may include timings (e.g., association timings) for atleast one corresponding UCI transmission uplink subframe, as describedbelow in connection with FIG. 5, FIG. 6 and FIG. 7. In someimplementations, the eNB 160 may generate and send an indicator based onthis determination 306 that indicates the set of downlink subframeassociations.

In one implementation, the eNB 160 may determine 306 that the set ofdownlink associations for the first cell may include the PDSCHassociation timing of a UCI transmission cell. For example, if the UCItransmission cell is a FDD cell and the first cell is a TDD cell, thefirst cell may follow the association timing of a FDD cell. In otherwords, if the first cell is a TDD cell, the first cell may follow theassociation timing of a FDD cell in PDSCH HARQ-ACK reporting for CA in ahybrid duplexing network.

In another implementation, the eNB 160 may determine 306 that the set ofdownlink subframe associations for first cell may include maintaining aPDSCH association timing of the first cell. For example, if the UCItransmission cell is a FDD cell and the first cell is a TDD cell, thefirst cell may maintain its own PDSCH association timing. For instance,the first cell may use a TDD UL-DL configuration as described below inconnection with FIG. 5 and FIG. 6.

In this implementation, the PDSCH HARQ-ACK bits of the first cell may bemultiplexed and reported on the PUCCH or PUSCH on the UCI transmissioncell. Alternatively, the FDD cells and the TDD cells may maintainindependent reporting mechanisms with their own PDSCH associationtimings.

The eNB 160 may receive 308 PDSCH HARQ-ACK information in the UCItransmission uplink subframe of the UCI transmission cell. For example,the eNB 160 may receive 308 PDSCH HARQ-ACK information in the UCItransmission uplink subframe corresponding to the determined 306 set ofdownlink subframe associations.

In one implementation, the eNB 160 may receive 308 PDSCH HARQ-ACKinformation on the PUCCH or PUSCH of one cell only. For example, if theUCI transmission cell is a FDD cell, the first cell is a TDD, and theset of downlink subframe associations for the first cell includes thePDSCH association timing of the UCI transmission cell, the eNB 160 mayreceive 308 PDSCH HARQ-ACK information for the TDD cell in an UL (e.g.,PUCCH or PUSCH) of the FDD cell. Because a DL is available in allsubframes on a FDD cell, the PDSCH HARQ-ACK on a TDD cell may always bereported on a corresponding UL of a FDD cell.

In another implementation where the UCI transmission cell is a FDD cell,the first cell is a TDD, but the set of downlink subframe associationsfor the first cell may include maintaining the PDSCH association timingof the first cell, the eNB 160 may also receive 308 PDSCH HARQ-ACKinformation on the PUCCH or PUSCH of one cell only. In thisimplementation, the PDSCH HARQ-ACK information for each cell may begenerated based on its own association timings. For example, a TDD cellmay follow a TDD DL-UL configuration as described in connection withFIG. 5, and a FDD cell may follow an association timing as described inconnection with FIG. 7. Therefore, PDSCH HARQ-ACK information for thefirst cell may be generated according to the association timing of thefirst cell. Additionally, the PDSCH HARQ-ACK information for the firstcell may be multiplexed and received 308 by the eNB 160 in the UCItransmission uplink subframe of the UCI transmission cell. In otherwords, the eNB 160 may receive 308 PDSCH HARQ-ACK information for theTDD cell in an UL (e.g., PUCCH or PUSCH) of the FDD cell.

In yet another implementation, where the FDD cells may have a UCItransmission cell and the TDD cells may have a second UCI transmissioncell, the eNB 160 may receive 308 PDSCH HARQ-ACK information in a UCItransmission uplink subframe to one or more cells. For example, asdescribed above, the FDD cells and TDD cells may maintain independentUCI reports. In this case, the FDD cells may include a UCI transmissioncell (e.g., a FDD anchor cell) and the TDD cells may include a secondUCI transmission cell (e.g., a TDD anchor cell). Multiple PUCCHs orPUSCHs may be reported concurrently on the FDD anchor cell and the TDDanchor cell. The eNB 160 may concurrently receive 308 PDSCH HARQ-ACKinformation for the FDD cells and TDD cells in a UCI transmission uplinksubframe corresponding to the UCI transmission cell or the second UCItransmission cell. Alternatively, the PDSCH HARQ-ACK information forboth the FDD cells and the TDD cells may be multiplexed and received 308in an UL (e.g., PUCCH or PUSCH) of one cell (e.g., a PCell).

FIG. 4 is a diagram illustrating one example of a radio frame 435 thatmay be used in accordance with the systems and methods disclosed herein.This radio frame 435 structure illustrates a TDD structure. Each radioframe 435 may have a length of T_(f)=307200·T_(s)=10 ms, where T_(f) isa radio frame 435 duration and T_(s) is a time unit equal to

$\frac{1}{\left( {15000 \times 2048} \right)}$seconds. The radio frame 435 may include two half-frames 433, eachhaving a length of 153600·T_(s)=5 ms. Each half-frame 433 may includefive subframes 423 a-e, 423 f-j each having a length of 30720·T_(s)=1ms.

TDD UL-DL configurations 0-6 are given below in Table (1) (from Table4.2-2 in 3GPP TS 36.211). UL-DL configurations with both 5 millisecond(ms) and 10 ms downlink-to-uplink switch-point periodicity may besupported. In particular, seven UL-DL configurations are specified in3GPP specifications, as shown in Table (1) below. In Table (1), “D”denotes a downlink subframe, “S” denotes a special subframe and “U”denotes an UL subframe.

TABLE (1) TDD UL-DL Downlink- Config- to-Uplink uration Switch-PointSubframe Number Number Periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U UD S U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms D S U U U D D D D D 4 10 ms  D S U U D D D D D D 5 10 ms  D S U D D D DD D D 6 5 ms D S U U U D S U U D

In Table (1) above, for each subframe in a radio frame, “D” indicatesthat the subframe is reserved for downlink transmissions, “U” indicatesthat the subframe is reserved for uplink transmissions and “S” indicatesa special subframe with three fields: a downlink pilot time slot(DwPTS), a guard period (GP) and an uplink pilot time slot (UpPTS). Thelength of DwPTS and UpPTS is given in Table (2) (from Table 4.2-1 of3GPP TS 36.211) subject to the total length of DwPTS, GP and UpPTS beingequal to 30720·T_(s)=1 ms. In Table (2), “cyclic prefix” is abbreviatedas “CP” and “configuration” is abbreviated as “Config” for convenience.

TABLE (2) Normal CP in downlink Extended CP in downlink Special UpPTSUpPTS Subframe Normal CP Extended CP Normal CP Extended CP Config DwPTSin uplink in uplink DwPTS in uplink in uplink 0  6592 · T_(s) 2192 ·T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s) 1 19760 ·T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 · T_(s) 25600· T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 · T_(s) 5  6592· T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 · T_(s) 23040 ·T_(s) 7 21952 · T_(s) — — — 8 24144 · T_(s) — — —

UL-DL configurations with both 5 ms and 10 ms downlink-to-uplinkswitch-point periodicity are supported. In the case of 5 msdownlink-to-uplink switch-point periodicity, the special subframe existsin both half-frames. In the case of 10 ms downlink-to-uplinkswitch-point periodicity, the special subframe exists in the firsthalf-frame only. Subframes 0 and 5 and DwPTS may be reserved fordownlink transmission. UpPTS and the subframe immediately following thespecial subframe may be reserved for uplink transmission.

In accordance with the systems and methods disclosed herein, some typesof subframes 423 that may be used include a downlink subframe, an uplinksubframe and a special subframe 431. In the example illustrated in FIG.4, which has a 5 ms periodicity, two standard special subframes 431 a-bare included in the radio frame 435.

The first special subframe 431 a includes a downlink pilot time slot(DwPTS) 425 a, a guard period (GP) 427 a and an uplink pilot time slot(UpPTS) 429 a. In this example, the first standard special subframe 431a is included in subframe one 423 b. The second standard specialsubframe 431 b includes a downlink pilot time slot (DwPTS) 425 b, aguard period (GP) 427 b and an uplink pilot time slot (UpPTS) 429 b. Inthis example, the second standard special subframe 431 b is included insubframe six 423 g. The length of the DwPTS 425 a-b and UpPTS 429 a-bmay be given by Table 4.2-1 of 3GPP TS 36.211 (illustrated in Table (5)above) subject to the total length of each set of DwPTS 425, GP 427 andUpPTS 429 being equal to 30720·T_(s)=1 ms.

Each subframe i 423 a-j (where i denotes a subframe ranging fromsubframe zero 423 a (e.g., 0) to subframe nine 423 j (e.g., 9) in thisexample) is defined as two slots, 2i and 2i+1 of lengthT_(slot)=15360·T_(s)=0.5 ms in each subframe 423. For example, subframezero (e.g., 0) 423 a may include two slots, including a first slot.

UL-DL configurations with both 5 ms and 10 ms downlink-to-uplinkswitch-point periodicity may be used in accordance with the systems andmethods disclosed herein. FIG. 4 illustrates one example of a radioframe 435 with 5 ms switch-point periodicity. In the case of 5 msdownlink-to-uplink switch-point periodicity, each half-frame 433includes a standard special subframe 431 a-b. In the case of 10 msdownlink-to-uplink switch-point periodicity, a special subframe mayexist in the first half-frame 433 only.

Subframe zero (e.g., 0) 423 a and subframe five (e.g., 5) 423 f andDwPTS 425 a-b may be reserved for downlink transmission. The UpPTS 429a-b and the subframe(s) immediately following the special subframe(s)431 a-b (e.g., subframe two 423 c and subframe seven 423 h) may bereserved for uplink transmission. It should be noted that, in someimplementations, special subframes 431 may be considered DL subframes inorder to determine a set of DL subframe associations that indicate UCItransmission uplink subframes of a UCI transmission cell.

FIG. 5 is a diagram illustrating some TDD UL-DL configurations 537 a-gin accordance with the systems and methods described herein. Inparticular, FIG. 5 illustrates UL-DL configuration zero 537 a (e.g.,“UL-DL configuration 0”) with subframes 523 a and subframe numbers 539a, UL-DL configuration one 537 b (e.g., “UL-DL configuration 1”) withsubframes 523 b and subframe numbers 539 b, UL-DL configuration two 537c (e.g., “UL-DL configuration 2”) with subframes 523 c and subframenumbers 539 c and UL-DL configuration three 537 d (e.g., “UL-DLconfiguration 3”) with subframes 523 d and subframe numbers 539 d. FIG.5 also illustrates UL-DL configuration four 537 e (e.g., “UL-DLconfiguration 4”) with subframes 523 e and subframe numbers 539 e, UL-DLconfiguration five 537 f (e.g., “UL-DL configuration 5”) with subframes523 f and subframe numbers 539 f and UL-DL configuration six 537 g(e.g., “UL-DL configuration 6”) with subframes 523 g and subframenumbers 539 g.

FIG. 5 further illustrates PDSCH HARQ-ACK associations 541 (e.g., PDSCHHARQ-ACK feedback on PUCCH or PUSCH associations). The PDSCH HARQ-ACKassociations 541 may indicate HARQ-ACK reporting subframes correspondingto subframes for PDSCH transmissions (e.g., subframes in which PDSCHtransmissions may be sent and/or received). It should be noted that someof the radio frames illustrated in FIG. 5 have been truncated forconvenience.

The systems and methods disclosed herein may be applied to one or moreof the UL-DL configurations 537 a-g illustrated in FIG. 5. For example,one or more PDSCH HARQ-ACK associations 541 corresponding to one of theUL-DL configurations 537 a-g illustrated in FIG. 5 may be applied tocommunications between a UE 102 and eNB 160. For example, an UL-DLconfiguration 537 may be determined (e.g., assigned to, applied to) aPCell. In this case, PDSCH HARQ-ACK associations 541 may specify PDSCHHARQ-ACK timing (e.g., a HARQ-ACK reporting subframe) for HARQ-ACKfeedback transmissions corresponding to the PCell. For SCell HARQ-ACKfeedback transmissions, the PDSCH HARQ-ACK associations 541corresponding to a reference UL-DL configuration in accordance with thefeedback parameters may be utilized.

A PDSCH HARQ-ACK association 541 may specify a particular (PDSCHHARQ-ACK) timing for receiving HARQ-ACK information corresponding to aPDSCH. A PDSCH HARQ-ACK association 541 may specify a reporting subframein which the UE 102 reports (e.g., transmits) the HARQ-ACK informationcorresponding to the PDSCH to the eNB 160. The reporting subframe may bedetermined based on the subframe that includes the PDSCH sent by the eNB160.

FIG. 6 illustrates a specific implementation of association timings of aTDD cell with UL-DL configuration one 637. FIG. 6 illustrates UL-DLconfiguration one 637 (e.g., “UL-DL configuration 1”) with subframes 623and subframe numbers 639. The PDSCH HARQ-ACK associations 641, PUSCHscheduling 643 and PUSCH HARQ-ACK associations 645 are illustrated. ThePDSCH HARQ-ACK associations 641 may indicate HARQ-ACK reportingsubframes corresponding to subframes for PDSCH transmissions (e.g.,subframes in which PDSCH transmissions may be sent and/or received). Inone implementation, the PDSCH HARQ-ACK reporting may occur on a PUCCH ora PUSCH. The PUSCH HARQ-ACK associations 645 may indicate HARQ-ACKreporting subframes corresponding to subframes for PUSCH transmissions(e.g., subframes in which PUSCH transmissions may be sent and/orreceived). In another implementation, the PUSCH HARQ-ACK reporting mayoccur on a PHICH or a PDCCH. In yet another implementation, the PUSCHscheduling 643 may include scheduling by an UL grant or PHICH (orePHICH) feedback from another cell.

As described above in connection with FIG. 5, there are seven differentTDD UL-DL configurations 537 a-g, all with different associationtimings. Furthermore, with inter-band TDD CA with different TDD UL-DLconfigurations, the association timing of one TDD cell may follow thetiming of a reference TDD UL-DL configuration. Moreover, in TDD CA withdifferent UL-DL configurations, the PDSCH HARQ-ACK timing may follow onereference TDD UL-DL configuration, and the PUSCH scheduling and HARQ-ACKtiming may follow another reference TDD UL-DL configuration. Thereference configurations may be the same or different.

FIG. 7 illustrates the association timings of a FDD cell. The FDD cellmay include paired downlink subframes 747 and uplink subframes 749. ThePDSCH HARQ-ACK associations 741, PUSCH scheduling 743 and PUSCH HARQ-ACKassociations 745 are illustrated. The PDSCH HARQ-ACK associations 741may indicate HARQ-ACK reporting subframes corresponding to subframes forPDSCH transmissions (e.g., subframes in which PDSCH transmissions may besent and/or received). In some implementations, the PDSCH HARQ-ACKreporting may occur on a PUCCH or a PUSCH. The PUSCH HARQ-ACKassociations 745 may indicate HARQ-ACK reporting subframes correspondingto subframes for PUSCH transmissions (e.g., subframes in which PUSCHtransmissions may be sent and/or received). In some implementations, thePUSCH HARQ-ACK reporting may occur on a PHICH or a PDCCH. In someimplementations, the PUSCH scheduling 743 may include scheduling by anUL grant or PHICH (or ePHICH) feedback from another cell.

A fixed 4 ms interval may be applied to the PDSCH HARQ-ACK associations741, PUSCH scheduling 743 and PUSCH HARQ-ACK associations 745. Forexample, each of the downlink subframes 747 and uplink subframes 749 maybe 1 ms. Therefore, the PDSCH HARQ-ACK transmission in subframe m+4 maybe associated with a PDSCH transmission in subframe m. A PUSCHtransmission in subframe n may be associated with the PUSCH scheduling743 in subframe n−4. Furthermore, the PUSCH HARQ-ACK transmission insubframe n+4 may be associated with the PUSCH transmission in subframen. For an FDD cell, for example, a fixed 4 ms may be applied to bothPDSCH and PUSCH timings.

FIG. 8 is a flow diagram illustrating a more specific implementation ofa method 800 for performing carrier aggregation by a UE 102. This may beaccomplished as described above in connection with FIG. 2, for example.A UE 102 may determine 802 a UCI transmission cell in a wirelesscommunication network with at least one FDD cell and at least one TDDcell. For example, the wireless communication network may be a hybridduplexing network in which carrier aggregation may be performed with oneor more FDD cell and one or more TDD cell. The UCI transmission cell maybe either a FDD cell or a TDD cell.

In one implementation, the UE 102 may determine 802 a UCI transmissioncell is a FDD cell or a TDD cell. This may be accomplished as describedabove in connection with FIG. 2. For example, the UCI transmission cellmay be a PCell, which may be a macro cell that is configured with FDD.In this implementation, the UCI may be reported on one cell only (e.g.,a PCell) for all of the cells (e.g., the FDD cells and TDD cells) in thehybrid duplexing network. For instance, the UCI may be reported on aPUCCH of the PCell.

The UE 102 may select 804 a first cell for FDD and TDD carrieraggregation. This may be accomplished as described above in connectionwith FIG. 2, for instance. For example, the UE 102 may select 804 a TDDcell as a first cell for carrier aggregation.

The UE 102 may determine 806 a PDSCH scheduling for the first cell. Forexample, with PDSCH self-scheduling, the PDSCH transmission for thefirst cell may be indicated by a corresponding PDCCH (or ePDCCH) on thefirst cell in the same subframe (e.g., the same transmission timeinterval (TTI)), or for a PDCCH (or ePDCCH) on the first cell in thesame subframe indicating a downlink semi-persistent scheduling (SPS)release.

With cross-carrier scheduling, the PDSCH transmission on the first cellmay be scheduled by the PDCCH (or ePDCCH) on another cell. For example,if the scheduling cell is a FDD cell (e.g., a PCell) and the first cellis a TDD cell, the PDSCH scheduling may follow the scheduling celltiming. On the other hand, if the scheduling cell is a TDD cell and thefirst cell is a FDD cell, a PDSCH transmission may be cross-carrierscheduled, for example, in the subframes where DL is allocated on thescheduling TDD cell.

The UE 102 may determine 808 a PUSCH scheduling 643, 743 and PUSCHHARQ-ACK associations 645, 745 for the first cell. For example, forPUSCH self-scheduling, the eNB 160 may schedule a PDCCH (or ePDCCH) witha downlink control information (DCI) format 0/4 and/or a PHICH (orePHICH) transmission on the first cell in a DL subframe intended for theUE 102. The UE 102 may adjust the corresponding PUSCH transmission insubframe n+k based on the PDCCH (or ePDCCH) and PHICH (or ePHICH)information, where k may be 4 for FDD, and k may be decided by (e.g.,based on) the TDD UL-DL configurations of the TDD cells according toTable 8.3-1 in 3GPP TS36.213. The PUSCH HARQ-ACK report may beassociated with the PUSCH transmission by a PHICH (or ePHICH) or PDCCH(or ePDCCH) on the first cell following the corresponding PUSCH HARQ-ACKassociations 645, 745.

With cross-carrier scheduling, the PUSCH scheduling 643, 743 and PUSCHHARQ-ACK associations 645, 745 for the first cell may be determined 808based on a scheduling cell timing. For example, the PUSCH transmissionon a cell may be scheduled by an UL grant or PHICH (or ePHICH) feedbackfrom another cell (e.g., a scheduling cell). With hybrid duplexingnetworks, if the scheduling cell is a FDD cell and scheduled cell is aTDD cell, the PUSCH transmission may be cross-carrier scheduled.

In one implementation, because UL may be allocated in all subframes ofthe scheduling FDD cell, the scheduled TDD cell may always becross-carrier scheduled with the FDD cell PUSCH scheduling 743 and PUSCHHARQ-ACK associations 745. For example, a fixed 4 ms PUSCH scheduling743 and the PUSCH HARQ-ACK associations 745 of a FDD cell (asillustrated in connection with FIG. 7) may be used to cross-carrierschedule a TDD cell.

On the other hand, if the scheduling cell is a TDD cell and the firstcell (e.g., the scheduled cell) is a FDD cell, the first cell may followthe scheduling cell timing on PUSCH scheduling 643 and PUSCH HARQ-ACKassociations 645. But the subframes with DL allocation in the TDDscheduling cell may not be able to schedule PUSCH transmission on thescheduled FDD cell. For example, if the first cell is a FDD cell, thefirst cell may have a fixed turnaround time of 8 ms for PUSCH scheduling743 and PUSCH HARQ-ACK associations 745. However, the TDD UL-DLconfigurations 537 a-g have at least 10 ms turnaround time. Therefore,the FDD cell timing (e.g., PUSCH scheduling 743 and PUSCH HARQ-ACKassociations 745) may not be applied for PUSCH scheduling and PUSCHHARQ-ACK associations for cross-carrier scheduling when the schedulingcell is a TDD cell and the scheduled cell (e.g., the first cell) is aFDD cell.

Additionally, the first cell may be a reference cell for cross-carrierPUSCH scheduling 643, 743 and PUSCH HARQ-ACK associations 645, 745. Forexample, if the PCell is a TDD cell, and the first cell is a FDD cell,the first cell may be configured as a reference cell for cross-carrierPUSCH scheduling 743 and PUSCH HARQ-ACK associations 745.

The UE 102 may determine 810 a set of downlink subframe associations forthe first cell that indicate at least one UCI transmission uplinksubframe of the UCI transmission cell. This may be accomplished asdescribed above in connection with FIG. 2, for example. The set ofdownlink subframe associations may include timings (e.g., PDSCH HARQ-ACKassociations 641, 741) for at least one corresponding UCI transmissionuplink subframe. This may be accomplished as described above inconnection with FIG. 2. For example, the UE 102 may determine 810 thatthe set of downlink associations for the first cell may include thePDSCH HARQ-ACK associations 641, 741 of a UCI transmission cell. If theUCI transmission cell is a FDD cell and the first cell is a TDD cell,the first cell may follow the PDSCH HARQ-ACK associations 741 of the UCItransmission cell configured with FDD.

The UE 102 may send 812 PDSCH HARQ-ACK information in the UCItransmission uplink subframe of the UCI transmission cell. This may beaccomplished as described above in connection with FIG. 2, for instance.For example, if the UCI transmission cell is a FDD cell, the first cellis a TDD, and the set of downlink subframe associations for the firstcell includes the PDSCH association timing of the UCI transmission cell,the UE 102 may send 812 PDSCH HARQ-ACK information for the TDD cell inan UL (e.g., PUCCH or PUSCH) of the FDD cell.

FIG. 9 is a flow diagram illustrating a more specific implementation ofa method 900 for performing carrier aggregation by an eNB 160. An eNB160 may determine 902 a UCI transmission cell in a wirelesscommunication network with at least one FDD cell and at least one TDDcell. This may be accomplished as described above in connection withFIG. 3, for instance. For example, the wireless communication networkmay be a hybrid duplexing network in which carrier aggregation may beperformed with one or more FDD cell and one or more TDD cell. The UCItransmission cell may be either a FDD cell or a TDD cell.

In one implementation, the eNB 160 may determine 902 a UCI transmissioncell is a FDD cell or a TDD cell. This may be accomplished as describedabove in connection with FIG. 2. For example, the UCI transmission cellmay be a PCell, which may be a macro cell that is configured with FDD.In this implementation, the UCI may be reported on one cell only (e.g.,a PCell) for all of the cells (e.g., the FDD cells and TDD cells) in thehybrid duplexing network. For instance, the UCI may be reported on aPUCCH of the PCell.

The eNB 160 may select 904 a first cell for FDD and TDD carrieraggregation. This may be accomplished as described above in connectionwith FIG. 3, for instance. For example, the eNB 160 may select 904 a TDDcell as a first cell for carrier aggregation.

The eNB 160 may determine 906 a PDSCH scheduling for the first cell. Forexample, with PDSCH self-scheduling, the PDSCH transmission for thefirst cell may be indicated by a corresponding PDCCH (or ePDCCH) on thefirst cell in the same subframe (e.g., the same transmission timeinterval (TTI)), or for a PDCCH (or ePDCCH) on the first cell in thesame subframe indicating a downlink semi-persistent scheduling (SPS)release.

With cross-carrier scheduling, the PDSCH transmission on the first cellmay be scheduled by the PDCCH (or ePDCCH) on another cell. For example,if the scheduling cell is a FDD cell (e.g., a PCell) and the scheduledcell is a TDD cell, the PDSCH scheduling may follow the scheduling celltiming. On the other hand, if the scheduling cell is a TDD cell and thescheduled cell is a FDD cell, a PDSCH transmission may be cross-carrierscheduled, for example, in the subframes where DL is allocated on thescheduling TDD cell.

The eNB 160 may determine 908 a PUSCH scheduling 643, 743 and PUSCHHARQ-ACK associations 645, 745 for the first cell. For example, forPUSCH self-scheduling, the eNB 160 may schedule a PDCCH (or ePDCCH) witha downlink control information (DCI) format 0/4 and/or a PHICH (orePHICH) transmission on the first cell in a DL subframe intended for theUE 102. The UE 102 may adjust the corresponding PUSCH transmission insubframe n+k based on the PDCCH (or ePDCCH) and PHICH (or ePHICH)information, where k may be 4 for FDD and k may be decided by the TDDUL-DL configurations of the TDD cells according to Table 8.3-1 in 3GPPTS36.213. The PUSCH HARQ-ACK report may be associated with the PUSCHtransmission by a PHICH (or ePHICH) or PDCCH (or ePDCCH) on the firstcell following the corresponding PUSCH HARQ-ACK associations 645, 745.

With cross-carrier scheduling, the PUSCH scheduling 643, 743 and PUSCHHARQ-ACK associations 645, 745 for the first cell may be determined 908based on a scheduling cell timing. For example, the PUSCH transmissionon a cell may be scheduled by an UL grant or PHICH (or ePHICH) feedbackfrom another cell (e.g., a scheduling cell). With hybrid duplexingnetworks, if the scheduling cell is a FDD cell and scheduled cell is aTDD cell, the PUSCH transmission may be cross-carrier scheduled.

In one implementation, because UL may be allocated in all subframes ofthe scheduling FDD cell, the scheduled TDD cell may always becross-carrier scheduled with the FDD cell PUSCH scheduling 743 and PUSCHHARQ-ACK associations 745. For example, a fixed 4 ms PUSCH scheduling743 and the PUSCH HARQ-ACK associations 745 of a FDD cell (asillustrated in connection with FIG. 7) may be used to cross-carrierschedule a TDD cell.

On the other hand, if the scheduling cell is a TDD cell and the firstcell (e.g., the scheduled cell) is a FDD cell, the first cell may followthe scheduling cell timing on PUSCH scheduling 643 and PUSCH HARQ-ACKassociations 645. But the subframes with DL allocation in the TDDscheduling cell may not be able to schedule PUSCH transmission on thescheduled FDD cell. For example, if the first cell is a FDD cell, thefirst cell may have a fixed turnaround time of 8 ms for PUSCH scheduling743 and PUSCH HARQ-ACK associations 745. However, the TDD UL-DLconfigurations 537 a-g have at least 10 ms turnaround time. Therefore,the FDD cell timing (e.g., PUSCH scheduling 743 and PUSCH HARQ-ACKassociations 745) may not be applied for PUSCH scheduling and PUSCHHARQ-ACK associations for cross-carrier scheduling when the schedulingcell is a TDD cell and the scheduled cell (e.g., the first cell) is aFDD cell.

Additionally, the first cell may be a reference cell for cross-carrierPUSCH scheduling 643, 743 and PUSCH HARQ-ACK associations 645, 745. Forexample, if the PCell is a TDD cell, and the first cell is a FDD cell,the first cell may be configured as a reference cell for cross-carrierPUSCH scheduling 743 and PUSCH HARQ-ACK associations 745.

The eNB 160 may determine 910 a set of downlink subframe associationsfor the first cell that indicate at least one UCI transmission uplinksubframe of the UCI transmission cell. The set of downlink subframeassociations may include timings (e.g., PDSCH HARQ-ACK associations 641,741) for at least one corresponding UCI transmission uplink subframe.This may be accomplished as described above in connection with FIG. 3,for instance. For example, the eNB 160 may determine 910 that the set ofdownlink associations for the first cell may include the PDSCH HARQ-ACKassociations 641, 741 of a UCI transmission cell. If the UCItransmission cell is a FDD cell and the first cell is a TDD cell, thefirst cell may follow the PDSCH HARQ-ACK associations 741 of the UCItransmission cell configured with FDD.

The eNB 160 may receive 912 PDSCH HARQ-ACK information in the UCItransmission uplink subframe of the UCI transmission cell. This may beaccomplished as described above in connection with FIG. 3, for instance.For example, if the UCI transmission cell is a FDD cell, the first cellis a TDD, and the set of downlink subframe associations for the firstcell includes the PDSCH association timing of the UCI transmission cell,the eNB 160 may receive 912 PDSCH HARQ-ACK information for the TDD cellin an UL (e.g., PUCCH or PUSCH) of the FDD cell.

FIG. 10 illustrates various components that may be utilized in a UE1002. The UE 1002 described in connection with FIG. 10 may beimplemented in accordance with the UE 102 described in connection withFIG. 1. The UE 1002 includes a processor 1063 that controls operation ofthe UE 1002. The processor 1063 may also be referred to as a centralprocessing unit (CPU). Memory 1069, which may include read-only memory(ROM), random access memory (RAM), a combination of the two or any typeof device that may store information, provides instructions 1065 a anddata 1067 a to the processor 1063. A portion of the memory 1069 may alsoinclude non-volatile random access memory (NVRAM). Instructions 1065 band data 1067 b may also reside in the processor 1063. Instructions 1065b and/or data 1067 b loaded into the processor 1063 may also includeinstructions 1065 a and/or data 1067 a from memory 1069 that were loadedfor execution or processing by the processor 1063. The instructions 1065b may be executed by the processor 1063 to implement one or more of themethods 200 and 800 described above.

The UE 1002 may also include a housing that contains one or moretransmitters 1058 and one or more receivers 1020 to allow transmissionand reception of data. The transmitter(s) 1058 and receiver(s) 1020 maybe combined into one or more transceivers 1018. One or more antennas1022 a-n are attached to the housing and electrically coupled to thetransceiver 1018.

The various components of the UE 1002 are coupled together by a bussystem 1071, which may include a power bus, a control signal bus and astatus signal bus, in addition to a data bus. However, for the sake ofclarity, the various buses are illustrated in FIG. 10 as the bus system1071. The UE 1002 may also include a digital signal processor (DSP) 1073for use in processing signals. The UE 1002 may also include acommunications interface 1075 that provides user access to the functionsof the UE 1002. The UE 1002 illustrated in FIG. 10 is a functional blockdiagram rather than a listing of specific components.

FIG. 11 illustrates various components that may be utilized in an eNB1160. The eNB 1160 described in connection with FIG. 11 may beimplemented in accordance with the eNB 160 described in connection withFIG. 1. The eNB 1160 includes a processor 1177 that controls operationof the eNB 1160. The processor 1177 may also be referred to as a centralprocessing unit (CPU). Memory 1183, which may include read-only memory(ROM), random access memory (RAM), a combination of the two or any typeof device that may store information, provides instructions 1179 a anddata 1181 a to the processor 1177. A portion of the memory 1183 may alsoinclude non-volatile random access memory (NVRAM). Instructions 1179 band data 1181 b may also reside in the processor 1177. Instructions 1179b and/or data 1181 b loaded into the processor 1177 may also includeinstructions 1179 a and/or data 1181 a from memory 1183 that were loadedfor execution or processing by the processor 1177. The instructions 1179b may be executed by the processor 1177 to implement one or more of themethods 300 and 900 described above.

The eNB 1160 may also include a housing that contains one or moretransmitters 1117 and one or more receivers 1178 to allow transmissionand reception of data. The transmitter(s) 1117 and receiver(s) 1178 maybe combined into one or more transceivers 1176. One or more antennas1180 a-n are attached to the housing and electrically coupled to thetransceiver 1176.

The various components of the eNB 1160 are coupled together by a bussystem 1185, which may include a power bus, a control signal bus and astatus signal bus, in addition to a data bus. However, for the sake ofclarity, the various buses are illustrated in FIG. 11 as the bus system1185. The eNB 1160 may also include a digital signal processor (DSP)1187 for use in processing signals. The eNB 1160 may also include acommunications interface 1189 that provides user access to the functionsof the eNB 1160. The eNB 1160 illustrated in FIG. 11 is a functionalblock diagram rather than a listing of specific components.

FIG. 12 is a block diagram illustrating one configuration of a UE 1202in which systems and methods for performing carrier aggregation may beimplemented. The UE 1202 includes transmit means 1258, receive means1220 and control means 1224. The transmit means 1258, receive means 1220and control means 1224 may be configured to perform one or more of thefunctions described in connection with FIG. 2, FIG. 8 and FIG. 10 above.FIG. 10 above illustrates one example of a concrete apparatus structureof FIG. 12. Other various structures may be implemented to realize oneor more of the functions of FIG. 2, FIG. 8 and FIG. 10. For example, aDSP may be realized by software.

FIG. 13 is a block diagram illustrating one configuration of an eNB 1360in which systems and methods for performing carrier aggregation may beimplemented. The eNB 1360 includes transmit means 1317, receive means1378 and control means 1382. The transmit means 1317, receive means 1378and control means 1382 may be configured to perform one or more of thefunctions described in connection with FIG. 3, FIG. 9 and FIG. 11 above.FIG. 11 above illustrates one example of a concrete apparatus structureof FIG. 13. Other various structures may be implemented to realize oneor more of the functions of FIG. 3, FIG. 9 and FIG. 11. For example, aDSP may be realized by software.

The term “computer-readable medium” refers to any available medium thatcan be accessed by a computer or a processor. The term“computer-readable medium,” as used herein, may denote a computer-and/or processor-readable medium that is non-transitory and tangible. Byway of example, and not limitation, a computer-readable orprocessor-readable medium may comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code in the form of instructions or data structures and that canbe accessed by a computer or processor. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-Ray® disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.

It should be noted that one or more of the methods described herein maybe implemented in and/or performed using hardware. For example, one ormore of the methods described herein may be implemented in and/orrealized using a chipset, an application-specific integrated circuit(ASIC), a large-scale integrated circuit (LSI) or integrated circuit,etc.

Each of the methods disclosed herein comprises one or more steps oractions for achieving the described method. The method steps and/oractions may be interchanged with one another and/or combined into asingle step without departing from the scope of the claims. In otherwords, unless a specific order of steps or actions is required forproper operation of the method that is being described, the order and/oruse of specific steps and/or actions may be modified without departingfrom the scope of the claims.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the systems, methods, and apparatus described herein withoutdeparting from the scope of the claims.

What is claimed is:
 1. A user equipment (UE) for performing carrieraggregation, comprising: a processor; memory in electronic communicationwith the processor, wherein instructions stored in the memory areexecutable to: send Hybrid Automatic Repeat RequestAcknowledgement/Negative Acknowledgement (HARQ-ACK) information inresponse to a Physical Downlink Shared Channel (PDSCH) transmissionbased on uplink HARQ-ACK timing, wherein, in a case that the UE isconfigured to use at least one frequency division duplexing (FDD) celland at least one time division duplexing (TDD) cell, the UE isconfigured to use a primary cell which is an FDD cell, the UE isconfigured to use a secondary cell which is a TDD cell, and the UE isnot configured to apply a dynamic UL/DL reconfiguration for thesecondary cell, the uplink HARQ-ACK timing for the TDD cell followsuplink HARQ-ACK timing for the FDD cell such that the HARQ-ACKinformation is sent four subframes after a subframe for the PDSCHtransmission.
 2. The UE of claim 1, wherein the HARQ-ACK information issent on one of a Physical Uplink Control Channel (PUCCH) or a PhysicalUplink Shared Channel (PUSCH).
 3. An evolved Node B (eNB) for performingcarrier aggregation, comprising: a processor; memory in electroniccommunication with the processor, wherein instructions stored in thememory are executable to: receive, from a user equipment (UE), HybridAutomatic Repeat Request Acknowledgement/Negative Acknowledgement(HARQ-ACK) information corresponding to a Physical Downlink SharedChannel (PDSCH) transmission for the UE based on uplink HARQ-ACK timing,wherein, in a case that the UE is configured to use at least onefrequency division duplexing (FDD) cell and at least one time divisionduplexing (TDD) cell, the UE is configured to use a primary cell whichis an FDD cell, the UE is configured to use a secondary cell which is aTDD cell, and the UE is not configured to apply a dynamic UL/DLreconfiguration for the secondary cell, the uplink HARQ-ACK timing forthe TDD cell follows uplink HARQ-ACK timing for the FDD cell such thatthe HARQ-ACK information is received from the UE four subframes after asubframe for the PDSCH transmission.
 4. The eNB of claim 3, wherein theHARQ-ACK information is received on one of a Physical Uplink ControlChannel (PUCCH) or a Physical Uplink Shared Channel (PUSCH).
 5. A methodfor performing carrier aggregation by a user equipment (UE), comprising:sending Hybrid Automatic Repeat Request Acknowledgement/NegativeAcknowledgement (HARQ-ACK) information in response to a PhysicalDownlink Shared Channel (PDSCH) transmission based on uplink HARQ-ACKtiming, wherein, in a case that the UE is configured to use at least onefrequency division duplexing (FDD) cell and at least one time divisionduplexing (TDD) cell, the UE is configured to use a primary cell whichis an FDD cell, the UE is configured to use a secondary cell which is aTDD cell, and the UE is not configured to apply a dynamic UL/DLreconfiguration for the secondary cell, the uplink HARQ-ACK timing forthe TDD cell follows uplink HARQ-ACK timing for the FDD cell such thatthe HARQ-ACK information is sent four subframes after a subframe for thePDSCH transmission.
 6. The method of claim 5, wherein the HARQ-ACKinformation is sent on one of a Physical Uplink Control Channel (PUCCH)or a Physical Uplink Shared Channel (PUSCH).
 7. A method for performingcarrier aggregation by an evolved Node B (eNB), comprising: receiving,from a user equipment (UE), Hybrid Automatic Repeat RequestAcknowledgement/Negative Acknowledgement (HARQ-ACK) informationcorresponding to a Physical Downlink Shared Channel (PDSCH) transmissionfor the UE based on uplink HARQ-ACK timing, wherein, in a case that theUE is configured to use at least one frequency division duplexing (FDD)cell and at least one time division duplexing (TDD) cell, the UE isconfigured to use a primary cell which is an FDD cell, the UE isconfigured to use a secondary cell which is a TDD cell, and the UE isnot configured to apply a dynamic UL/DL reconfiguration for thesecondary cell, the uplink HARQ-ACK timing for the TDD cell followsuplink HARQ-ACK timing for the FDD cell such that the HARQ-ACKinformation is received from the UE four subframes after a subframe forthe PDSCH transmission.
 8. The method of claim 7, wherein the HARQ-ACKinformation is received on one of a Physical Uplink Control Channel(PUCCH) or a Physical Uplink Shared Channel (PUSCH).